A gripper device, and more specifically to a gripper device which is particularly suitable for placing an annular member onto a workpiece.
Various types of mechanical grippers for use on automatic machines and/or robotic tools for holding, positioning and/or locating a particular workpiece or part are known. Some of the known grippers are disclosed in various U.S. Letters Patents, e.g. U.S. Pat. Nos. 4,611,846; 4,913,481; 5,125,708; 5,163,729; 5,620,223 and 5,967,581. While the grippers disclosed in these patents may be satisfactory for positioning or gripping a workpiece of a given configuration or shape, they are not suitable for gripping an annular member such as a washer, O-ring and the like, or to position the same onto a workpiece.
An object of this invention is to provide a gripper for use with a machine or robotic tool that is particularly suitable for gripping an annular shape member, e.g. an xe2x80x9cOxe2x80x9d ring and/or for placing the same onto a workpiece.
Another object is to provide a gripper for positioning an annular member that is relatively simple, inexpensive to manufacture, and positive in operation.
Another object is to provide a gripper particularly suitable for gripping and/or positioning an expandable annular member which can be readily adjusted to handle expandable annular members of various sizes within a given range of sizes.
The foregoing objects and other features and advantages are attained by a gripper assembly which includes a housing having formed therein a pair of piston chambers, each having a piston reciprocally mounted therein. A cover plate provides a closure for the housing. The cover plate is formed with a plurality of radial slideways, each having a slide reciprocally disposed within a corresponding slideway. Each of the slides has a plurality of apertures or holes for adjustably positioning a gripper finger thereon.
The piston in one of the piston chambers is provided with a piston rod which extends beyond the associated piston chamber. A plurality of links interconnects each of the respective slides to the projected end of the piston rod whereby actuation of the piston imparts a relative radial sliding movement to each of the slides. Also formed in the cover plate are a plurality of through holes.
The piston in the other piston chamber includes a piston head having a plurality of circumferentially spaced longitudinally extending arms having connected thereto a pusher disposed in alignment with the through holes formed in the cover plate. Between the adjacent pairs of piston arms there is a spring for exerting a spring bias on the piston head. A compression ring is supported within the housing to maintain the springs in compression. The arrangement is such that fluid pressure applied to the first mentioned piston will effect the displacement thereof causing the links to radially displace the connected slides outwardly whereby the fingers mounted on the respective slides will grip and hold an annular member thereon. Subsequent actuation of the other piston will cause the pushers to project through the through holes of the cover plate to push the annular member off the slide fingers and onto a workpiece positioned to receive the annular member. Upon the push off of the annular member from the slide fingers, the springs acting on the pusher piston will bias the pusher piston and associated pushers toward the inoperative position or retracted position.